Oxidative copolymerization of p-phenylenediamine

Abstract

The sulfonation of poly(p-phenylenediamine) (P(pPD)) was achieved by oxidative copolymerization of p-phenylenediamine (pPD) and 3-aminobenzenesulfonic acid (3ABSA) monomers using ammonium persulfate ((NH4)2S2O8). The yield, molecular weight, solubility, degree of sulfonation, molecular structure, and thermal stability of the pPD-co-3ABSA copolymers were shown to be largely dependent on the degree of sulfonation. The solubility of the pPD-co-3ABSA copolymers in most solvents was significantly improved compared to the parent P(pPD) polymer due to the steric effect of sulfonic groups (–SO3H). Conversely, the yield, molecular weight, and conductivity values obtained for pPD-co-3ABSA copolymers were lower than those obtained for the P(pPD) polymer, which was attributed to the steric hindrance and the electron withdrawing effects of the sulfonic groups on the aromatic rings. TGA results revealed that P (pPD) and pPD-co-3ABSA copolymers have good thermal stability and decompose at temperatures above 300 C in nitrogen.